In recent years fuel-cell vehicles have been developed in which a motor is supplied with electric power generated by a fuel cell system to drive wheels. In the fuel cell system, the chemical reaction of hydrogen gas and oxygen as reaction gas generates electric power in a fuel cell stack (hereafter simply referred to as “fuel cell”). Here, the oxygen is taken in via a compressor from air and the hydrogen gas is supplied from a high-pressure fuel cylinder.
The fuel-cell vehicle has a hydrogen sensor for sensing hydrogen gas and a mounting structure in which the hydrogen sensor is mounted via a bracket between roof members (see, for example, JP-A No. 291849/2003). According to such a mounting structure, the hydrogen sensor is arranged at a high position to be able to improve the accuracy of sensing hydrogen leakage, which is preferable.
The structure disclosed in JP-A No. 291849/2003 is applied to a four-wheeled vehicle having a roof and it is difficult to apply the structure to a two-wheeled vehicle having no roof. Moreover, a two-wheeled vehicle is smaller in size than a four-wheeled vehicle and hence it is desired to utilize a mounting space effectively.
Further, a common fuel-cell vehicle is provided with a liquid-cooled cooling system for cooling the fuel cell and it is desired to more surely sense that hydrogen gas is mixed in the pipe of the cooling system.
The present invention has been made in consideration of such a problem. One object of the present invention is to provide a fuel-cell two-wheeled vehicle having a sensor mounted in an effective arrangement space and capable of sensing hydrogen gas more surely. Another object of the present invention is to provide a fuel-cell two-wheeled vehicle that more surely senses hydrogen gas mixed in the pipe of a cooling system.